When a computer system is powered on, a boot loader is first executed to boot startup of the system and initialization of hardware.
The boot loader is usually stored using Nand-Flash. When the computer system is powered on, a central processing unit (CPU) may read the boot loader from the Nand-Flash, and write the boot loader into a random access memory (RAM) for execution.
The Nand-Flash usually stores data in blocks. In a write process, the Nand-Flash easily generates a bad block and the bad block cannot be read or written. In this case, once a Block that stores the boot loader becomes a bad block, system startup fails.
In addition, if a power failure occurs in an upgrade process of the boot loader, the boot loader in the Nand-Flash may also be damaged, and the system startup fails.